1. Field of the Invention
The present invention relates to an optical transceiver that receives and sends signal light transmitted in an optical fiber.
2. Related Prior Art
A conventional optical transceiver comprises a frame, an optical receptacle, an optical subassembly, a substrate for installing an electronic circuit, and a cover. The frame supports the optical receptacle, the optical subassembly and the substrate. Within the optical subassembly, a semiconductor optical device is installed for sending/receiving signal light. The head portion of the optical subassembly is positioned in the optical receptacle. When an optical connector mate with the optical receptacle, an optical fiber in the optical connector optically couples to the optical subassembly in the optical receptacle, thereby coupling the optical fiber to the semiconductor device mounted in the optical subassembly. The electronic circuit receives an electric signal from the outside of the optical transceiver, reshapes this signal and sends the reshaped signal to the optical subassembly, or the electronic circuit receives an electric signal from the optical subassembly, amplifies this signal and output the amplified signal to the outside of the optical transceiver. The cover not only protects the optical receptacle, the optical subassembly and the substrate but also effectively dissipates heat generated within the optical transceiver to the outside.
The shape of the optical receptacle, including the head portion of the optical subassembly that is placed in the optical receptacle, is regulated by the standard of the optical connector. Namely, the positional relation between the optical receptacle and the optical subassembly must be in accordance with the standard of the optical connector. This positional relation must have an accuracy of a few tenths of micron meters to maintain the optical coupling efficiency therebetween, whereby the optical subassembly and the optical receptacle are necessary to fix rigidly to the frame.
On the other hand, the substrate provides an electrical plug in a side opposing to the optical subassembly for mating with an electrical connector provided on the main board where the optical transceiver is installed thereon. The relative position to the frame and the cover of this electrical plug is also in accordance with the standard of the electrical connector, whereby the substrate is rigidly fixed to the frame. Moreover, from a viewpoint of heat dissipation, a primary portion of the optical subassembly, where the semiconductor optical device is installed thereon, is preferable to be rigidly fixed to the frame. Thus, the optical receptacle, the optical subassembly and the substrate, these are mounted on the frame, are strictly requested in their dimensions and positions on the frame. However, some tolerance always accompanies in the design and the assembly of these parts, and in the conventional optical transceiver, this tolerance is only compensated by the connection between the optical assembly and the substrate. Accordingly, mechanical stress concentrates on a portion where the optical subassembly is connected to the substrate, which results on inferior reliability. The optical subassembly may be fixed to the frame via an elastic material as a cushion to relax the mechanical distortion therebetween. However, such elastic material generally has less thermal conductivity.